Amino acid racemisation dating
With these measurements, scientists can estimate the rate at which one enantiomer is converted to the other.Currently, these techniques are used to estimate the age of fossils, determine the life span of bowhead whales, and detect evidence of extraterrestrial life.The rate itself of hydrolysis "depends on the strength of the individual peptide bonds, which in turn is determined by the characteristics of the amino acids on either side of the bond, the presence of water and the temperature."All of these are confounding factors, which, if not known exactly over extended periods of time, would play havoc with any sort of age determinations.Even the process of preparing a specimen for racemic dating can affect the D/L ratio.So, by examining how many have shifted, one can estimate the age of the sample.
Then one could use this as an independent test on other dating schemes.Chemical Whale Tales Since 1981, whale hunters in Alaska have found at least six harpoon heads in bowhead whales that they have killed in the Beaufort Sea, southwest of the Arctic Ocean. Anthropologists at the Smithsonian Institution (Washington, DC) estimate that they are between 130 and 200 years old and were probably used by Inupiat hunters in the late 1700s.This circumstantial evidence led Craig George and fellow researchers at the Department of Wildlife Management (North Slope Borough, Barrow, AK) to believe that bowhead whales, named for their exaggerated jaw curve, could have a life span of more than 200 years.(To hear a radio interview with George, visit The only other animals with similarly long life spans are the giant tortoise and the giant clam, which some have claimed can live about 150 and 220 years, respectively.An article in the Dec 13, 1996 issue of Science, page 1842, discusses dating based on the amino acid racemization technique. ) form, but with time some transform to the D (right) form.